Field of the Invention
The present invention relates to a fill level gauge with a rinsing device for rinsing a fill level sensor.
Background of the Invention
The current state of knowledge is as follows.
Fill level gauges for measuring the fill level of liquids and bulk goods in a container are known from prior art and widely used in industrial environments. The selection of the suitable measuring method essentially depends on whether liquids or bulk goods are processed.
For example, the detection of a fill limit using microwaves is based on the transceiver principle. Microwave pulses emitted by a transmitter and passing through an empty container are registered by a receiver; however, in a full container they are absorbed by the medium at least partially. The exceeding of a limit can be concluded from the ratio of the measured pulse rates.
Radar fill level gauges work with radar sensors. Here, high-frequency radar pulses are emitted by an antenna and reflected by the surface of the filling material. The travel time of the reflected radar pulse is directly proportional to the distance traveled. With known container geometries, the fill level can be calculated from this.
In order to determine the height of the fill level in a container, the fill level sensor is usually directly aligned to the interior of the container. The measurements are performed while the container is being filled.
A problem arising here during the measurement of the fill level is the soiling of the sensor by dust, for example, which is raised during the filling process of the container and adheres to the sensor. The measuring of the fill level in coking plants is a good example, here. Such soiling changes the signal which is detected. When the soiling is excessive, the signal cannot be detected any longer, and the height of the fill level can no longer be determined. In such cases in prior art, an error message is issued which indicates that a signal is no longer being received. Potential causes for the error are then listed, e.g. a defective antenna, an interrupted signal line, or excessive soiling of the antenna.
A similar problem may also occur when the detector overheats. This case may arise, for example, when the detector is used in environments in which the temperature is very high, as is the case in smelters, for example.
When the detector overheats, this may also lead to the measurement becoming falsified, and thus measuring cannot reliably be performed any more.
For these reasons, rinsing and/or cooling connections are frequently provided for in radar fill gauges, for example, with which the fill level sensor can be rinsed and/or cooled.
DE 10 2004 033 033.6, for example, discloses such a fill level gauge—antenna arrangement for radar fill level gauges with a pipeline system for guiding a medium through it, which may be gaseous or liquid, with the antenna arrangement being embodied for supplying a coolant to the components of the antenna which heat up.
Such fill level gauges are usually rinsed continuously with a cooling or rinsing fluid in order to avoid interruptions. In order to ensure an uninterrupted operation of the fill level gauge, a large quantity of rinsing and/or cooling fluid is consumed.
Accordingly, the objective of the present invention is to provide fill level gauges not showing these disadvantages.
This objective is attained in a fill level gauge according to claim 1, as well as a method for rinsing a fill level sensor according to claim 21. Advantageous embodiments are disclosed in the dependent claims.